A comet is a bright object with a long tail that travels around the sun.
Halley's Comet is going to come back in 2061.
comet in British English
(ˈkɒmɪt)
noun
a celestial body that travels around the sun, usually in a highly elliptical orbit: thought to consist of a solid frozen nucleus part of which vaporizes on approaching the sun to form a gaseous luminous coma and a long luminous tail
Derived forms
cometary (ˈcometary) or cometic (kɒˈmɛtɪk)
adjective
Word origin
C13: from Old French comète, from Latin comēta, from Greek komētēs long-haired, from komē hair
comet in American English
(ˈkɑmɪt)
noun
a small, frozen mass of dust and gas revolving around the sun in a parabolic or elliptical orbit: as it nears the sun it vaporizes, forming a coma and, usually,a long tail of ions that points away from the sun
Derived forms
cometary (ˈcometˌary) (ˈkɑməˌtɛri)
adjective or coˈmetic (koʊˈmɛtɪk)
Word origin
ME comete < OE cometa & OFr comete, both < L cometa < Gr komētēs, lit., long-haired (star) < komē, lit., hair of the head